This invention relates to a liquid coffee product which may be used as a refreshing beverage or topping. The invention also provides a method for the production of the liquid coffee product.
Ready-to-serve coffee-based beverages are becoming increasing popular. Very often, these beverages contain milk solids or a whitener. Apart from providing a beverage having an appearance and taste similar to that of whitened coffee, the milk solids or whitener performs the function of masking some of the harsher flavors which may arise in ready-to-drink coffee beverages. When served chilled, however, coffee beverages which contain milk solids or a whitener are perceived to be less refreshing than black coffee beverages.
Ready-to-serve black coffee beverages are available; especially in Asian markets. To avoid harsh flavors, however, these beverages contain less than 2% by weight of soluble coffee solids. Also, these beverages are usually heavily sweetened. Despite this, these beverages are often still characterized by harsher, dirty flavors and often do not provide very refreshing beverages when consumed chilled.
Therefore, there remains a need for a black, ready-to-serve, coffee-based product which has a fresh, clean flavor, and this invention addresses this need.
Accordingly, in one aspect, this invention provides a ready-to-serve coffee product comprising an aseptically filled container, and a black, coffee containing liquid in the container; where the liquid has a fresh, clean taste. Preferably, the liquid has a coffee solids concentration of above about 2% by weight; and more preferably above about 2.2% by weight. Also, the liquid preferably has a ratio of aldehydes to furans of less than about 1:12.
In another aspect, the black, coffee containing liquid is produced by a process comprising the steps of extracting coffee solids from roast and ground coffee at a draw-off ratio of less than about 3 to produce a coffee extract; and adjusting the concentration of soluble coffee solids in the coffee extract to less than about 5% by weight under oxygen-reduced conditions to provide the coffee containing liquid. Preferably, the coffee containing liquid is aseptically filled into the container.
In yet another aspect, this invention provides a method for providing a chilled coffee beverage, by the steps of providing an aseptically filled container containing a black, coffee containing liquid; the liquid having a fresh, clean taste and a concentration of soluble coffee solids above about 2 to 2.2% by weight; opening the container; and pouring the black, chilling the coffee containing liquid, such as by pouring it over ice particles from shaved or crushed ice.
In a further aspect, this invention provides a dessert topping product which comprises an aseptically filled container; and a black, coffee containing liquid in the container; the liquid having a fresh, clean taste and a concentration of soluble coffee solids above about 2% by weight. The coffee containing liquid may contain a sweetener and may contain flavors.
Embodiments of the invention are now described by way of example only. This invention provides a liquid, black coffee product which has a fresh, clean taste with little objectionable bitter and harsh notes and which is in ready-to-serve form. The liquid coffee product may contain high amounts of soluble coffee solids; for example above 2% by weight. In general, conventional black, liquid coffee products which are provided in ready-to-serve form have a soluble coffee solids content of about 1% and below. Concentrations of soluble coffee solids above about 1.5% by weight generally cannot be used in conventional products since the product would then have objectionable harsh and bitter notes.
In this specification, the term xe2x80x9cdraw-off ratioxe2x80x9d means the ratio of the weight of the coffee extract removed from the extraction system to the weight of fresh coffee introduced into the extraction system.
The term xe2x80x9cFo valuexe2x80x9d means the equivalent time in minutes for a product held at a temperature of 121xc2x0 C.
In this specification, the term xe2x80x9cFuransxe2x80x9d means compounds of the furan class including 2-methylfturan.
The term xe2x80x9cDiketonesxe2x80x9d means aroma compounds of the diketone class including 2,3-butanedione, and 2,3-pentanedione.
The term xe2x80x9cAldehydesxe2x80x9d means aroma compounds of the aldehyde class including isobutyraldehyde, 3-methyl-butanal, and 2-methyl-butanal.
The term xe2x80x9cPyrrolesxe2x80x9d means compounds of the pyrrole class including 1-methyl-1H-pyrrole.
The term xe2x80x9cppm methyl butyratexe2x80x9d means the calculated amount of a compound based upon the response factor of methyl butyrate.
The liquid, black coffee product is produced by preparing a coffee extract. The coffee extract is prepared by subjecting roasted coffee beans to extraction under mild temperature conditions and using a low draw-off ratio. The roasted coffee beans are preferably ground prior to extraction. Any suitable beans or blends or beans may be used. Naturally, the better the bean quality, the better the product finally produced.
The extraction may be carried out in a counter-current manner in one or more extraction vessels. Any suitable extraction vessels may be used; for example fixed bed reactors or continuous counter-current extractors. The choice and design of the vessels is a matter of preference and has no critical impact on the process. Further, if fixed bed reactors are used, the extraction liquid may be caused to flow upward through the reactor or downward through the reactor, as desired. The extraction is conveniently carried out in a battery of fixed bed reactors connected such that extraction liquid may flow through them in series.
The extraction is carried out under relatively mild conditions such that little or no hydrolysis of the coffee solids takes place. Therefore, the temperature of the extraction liquid used to extract the coffee solids is preferably below about 140xc2x0 C.; and more preferably below about 120xc2x0 C.
The extraction liquid is conveniently hot water which may be, but need not necessarily be, deoxygenated. Coffee extract may also be used as the extraction liquid but this is less preferred.
The draw-off ratio for the extraction is preferably less than about 3:1; more preferably less than about 2:1. It is surprisingly found that extraction using low draw-off ratios provides a coffee extract with a cleaner, fresher taste with fewer harsh notes.
The coffee extract obtained will usually have a concentration of coffee solids in the range of about 8% to about 15% by weight. The coffee extract is maintained under reduced oxygen conditions. If desired, oxygen scavengers or antioxidants such as ascorbic acid may be added to the coffee extract. If it is necessary to store the coffee extract for any significant length of time, storage is best conducted under refrigerated conditions.
The coffee extract is then formulated to provide the liquid coffee product. Ingredients such as sweeteners, flavors, buffers and the like may be added and the concentration of the soluble coffee solids reduced to the desired level. Ordinarily, the concentration of the soluble coffee solids will be adjusted to about 0.8% to about 3.5% by weight; more preferably about 2% to about 3% by weight.
If used, examples of suitable buffers include sodium and potassium bicarbonate, di-sodium and di-potassium phosphates, and sodium and potassium citrates. Various combinations of these buffers may also be used. The buffering system used will depend largely upon regulations in the various countries.
Further, if used, examples of suitable sweeteners include sugar, artificial sweeteners such as saccharin, cyclamates, acetosulfame, sucralose, L-aspartyl based sweeteners such as aspartame, and mixtures of sugar and artificial sweeteners.
Suitable flavors which may be used include vanilla, bourbon, whisky, chocolate, and the like.
The mixture of all components may then be subjected to homogenization if necessary. Oxygen-reduced conditions are preferably used during formulation of the liquid coffee product.
The homogenized mixture is then preferably subjected to ultra high temperature (UHT) treatment. This may be accomplished by rapidly heating the mixture to a temperature above about 135xc2x0 C.; for example to about 140xc2x0 C. to about 150xc2x0 C. This may be carried out in a suitable heat exchanger or by direct injection of steam into the liquid beverage mix. Suitable heat exchangers are plate heat exchangers, tubular heat exchangers and scraped surface heat exchangers; plate heat exchangers being particularly suitable.
The mixture is held at the raised temperature for a time less than about 2 minutes but sufficient to provide a Fo value of at least about 4. Depending upon the temperature to which the mixture is heated, the mixture is conveniently held at the temperature for about 5 seconds to about 60 seconds. The Fo value reached is preferably about 5 for products which will be cold vended. For products which will be hot vending, the Fo value may be about 60 to 75.
The treated mixture is then cooled to a temperature below about 60xc2x0 C.; for example to less than about 40xc2x0 C. This may be conveniently accomplished by using a suitable heat exchanger or by flash cooling the beverage. Again a plate heat exchanger is a particularly suitable heat exchanger. Flash cooling is especially suitable if the mixture was heated using direct injection of steam since the introduced steam may then be flashed off. Otherwise the increase in water content must be accounted for when preparing the mixture.
If needed and not added earlier, suitable buffers and other additives may be may be added at this point.
The liquid coffee product obtained is then aseptically filled into suitable containers. Standard aseptic filling machinery may be used. The containers are then sealed and stored. The aseptic filling is preferably carried out under reduced oxygen conditions.
If desired, although less preferable, the liquid coffee product may be filled into suitable containers and then retorted. In this case, aseptic filling is not necessary. The filling is preferably carried out under reduced oxygen conditions. Standard filling and retorting machinery may be used.
The products obtained are characterized by a fresh, clean taste with little of the harsh, bitter notes of most conventional ready-to-drink black coffee beverages. This is despite the fact that the product may contain raised levels of soluble coffee solids. The products may be consumed in many different ways. For example, the product may be poured over crushed or shaved ice to provide a refreshing beverage. Alternatively, the product may be used as a topping on desserts such as ice cream. Further, the product may be frozen and served as a dessert; especially when mixed with other frozen desserts or fresh whole milk.
It is found that the products contain an advantageous ratio of aldehydes to furans of less than about 1:12; more preferably about 1:4 to about 1:10. It is believe that these characteristics have a favorable impact on the flavor of the products.